Just wondering if anybody has a mother who is mean and hurtful one minute and nice as ninepins the next?

I’ve already been in this forum in the past and everyone was so helpful and made me feel like I wasn’t alone. Anyway, my next saga in this story… my mother who is 72 has health problems including Parkinson’s I am her main caregiver. My father passed away 21 years ago and I have been her main caregiver since then. I used to go up every day, 7 days a week but over the years I’m just too tired I’m 46. I started to cut down the time as it was getting too much trying to run 2 homes and with three children of my own and I work nightshift and I still goes to my mother’s 3 times a week and has twice daily check-ins by the telephone (sometimes more) she is increasingly getting hard work. Something happened to another member of the family’s son and she wasn’t told bearing in mind I knew nothing of it she then goes off arguing nobody does anything for her, she sick of my voice she’s had it for the last 20 years, she doesn’t want me to go up anymore she’ll do everything for herself. How she is going on recently it’s just really affecting my mental health. I just feel like calling in the towel I just can’t cope with her but then I feel guilty. I’m just so tired of how she makes me feel even at 46. Do I call her bluff?